Note: I originally posted this in another thread (which ended up being about what a pet is for what ever reason), so this post might not make entirely sense without this fore-note.
Mesmers can be a pet class, although they don’t play as one by default. Think about all the phantasm traits (and utilities) designed around keep them alive – the health ones, the recharges ones, and arguably the damage increasing ones (it at leasts makes you want to keep them alive).
The only issue I see with this in particular is the disparity in different fights – it causes a problem of balance. If for example you go as a phantasm build (which are quite popular)-
Fight A you are against a walking wastelands of a boss, spewing aoe and cleaves – this type of boss is fairly common. How long do you think your phantasms are going to last? With only being able to get one attack off per phantasm, and with 60-80% of your damage coming from phantasms, you would expect phantasm damage to be balanced around only getting one attack off per phantasm cooldown – so you would expect quite high damage from one attack.
Fight B you are against a boss that can be controlled and does little or moderate aoe damage/cleave – this type of boss is fairly common. How long do you think your phantasms are going to last? I would say that it is fairly easy to get three phantasms up and replace them on cooldowns for extra attacks (replaced phantasms attack immediately). I can expect each cooldown to get off many attacks and I would expect phantasm damage to be balanced around this – so I would expect medium-low damage from one attack.
Do you see the problem?
A way of simplifying the problem is to describe the problem as an uptime problem. In fight A the uptime of the phantasms is very low. In fight B the uptime of the phantasms is very high.
One way to solve this is make the uptimes more reliably equal. You could for example make phantasms resistant to aoe so that uptime is likely to be high, and then balance around this. Since we do have traits that seem to suggest that phantasms are meant to be around for a little while it seems this might be a good idea. Perhaps make it a trait so only certain builds can get it, specialising them for high uptime, like the phantasm build.
Another way to solve it is to make the cooldown much lower – again, maybe trait it (more than it does currently, but deeper in). With a low cooldown you can make it so that you can get phantasms up as much as they would be able to attack anyway, meaning you can once again balance around a high uptime. You are limited by only 3 phantasms so being able to get them out any faster doesn’t increase damage by much in longer fights, but still allows a more consistent form of damage. Would also help with burst for phantasm builds in solo pve.
We should also look at pvp. At first this seems much harder because of the sheer range of different “personalities” of your opponents. Some might kill your phantasms the moment they even glimpse those transparent glowing figures. Others may make a beeline for you and go for broke. In actual fact in really just comes down to uptime again and the sheer range difference that make it harder to balance.
The real difficult with the pvp is that you almost have to assume low uptime, because our opponents are intelligent enough to kill anything that is a threat very quickly if they can (and they can kill phantasms just by blinking, so that’s a certainty).
That said, most of the time they do this by offchance or large aoe, relying on the stupidity and low health of our phantasms to make it impossible to keep phantasms alive for anything more than one attack. So perhaps the same aoe resistance as stated in the above paragraphs would help here too. Also, the fast cooldown phantasms would solve the problem again by allowing for a high uptime even though you assume only one attack per cooldown.
So in fact, both of those solutions would, as I see it, work to make balancing phantasm damage. This can then mean we are not underpowered or overpowered in different situations, which is the real issue.
Note, that I am entirely happy to have phantasm only get one attack off or many, to either play it more like a disposable attack or more like a pet – as long as it is balanced. The traits could allow such choice and thus I see it as a good platform for choosing low or high uptime phantasms.